<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		
		<script type="text/javascript">
			new Promise((resolve,reject)=>{
					setTimeout(()=>{
						resolve("aaa")
					},1000)
			}).then(res=>{
				console.log(res);
				console.log("第一层处理完成");
				return new Promise((resolve)=>{
						setTimeout(()=>{
							resolve(res+'111')
						},1000);
				})
			}).then(res=>{
				console.log(res);
				console.log("第二层处理完成");
				return res+'222'
			})
			
			
			
		</script>
		
	</body>
</html>
